#include <stdio.h>

int main()
{
    float l;
    float s = 0.0f;
    float p = 2.0f;
    int n = 0;
    scanf("%f", &l);
    while (s < l)
    {
        s += p;
        p *= 0.98f;
        ++n;
    }
    printf("%d", n);
    return 0;
}